Brush holder mounting



Aug. 24, 1948. J. E. PASTORET ETAL 2,447,652

BRUSHHOLDER-MOUNTING Filed April 19, 1947 INVENTORS John E. Pasta/e2 and John W. Moi ram fi u- WITNESSES:

ATTORNEY Patented Aug. 24, 1948 BRUSH. HOLDER MOUNTING John E. Pastoret and John W. Morrow, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 19, 1947, Serial No. 742,558

4 Claims. 1 Our invention relates to an improved form of brushholder-mounting, for supporting the brushholders of a dynamo-electric machine. While our invention has desirable features of general utility, it was more particularly designed for an ex-' plosion-resistant motor, for use on mine-locomotives. On these explosion-resistant motors, the specifications of the United States Bureau of Mines require a minimum number of holes through the motor-frame, with special limitations regarding the non-removability of the bolts or studs which pass through those holes. Previous attempts to meet such specifications have resulted in extremely awkward brushholdermountings, which were very inconvenient to the customer, in his efforts to adjust or service the brushholders from time to time, and quite costly to the manufacturer, in assembling the mounting, and also somewhat deficient in regard to the degree of accuracy which was obtainable in the course of manufacture.

The object of our present invention is to provide a novel form of brushholder-mounting, such as is hereinafter described and claimed, and illustrated in the drawing, wherein Figure 1 is a longitudinal sectional view of the top half of one end of a mine-locomotive mo-, tor, embodying our invention in an illustrative form of embodiment;

Fig. 2 is a sectional view through the end-wall of the motor-frame, on the section-line IIII of Fig. 1, showing a plan view of the brushholdermounting; and

Fig. 3 is an end view of the inner support-block of the brushholder-mounting, as seen from the inside of the machine.

We have illustrated our invention as being applied to a direct-current traction-motor, designed for use on a mine-locomotive. The motor has a stator-frame I, having an end-wall 2 at the commutator-end of the machine. The end-wall 2 carries a bearing 3 for the shaft 4 of the rotora fiat, accurately machined, brushholder-sup-' porting surface II), which can be very accurately and very economicall provided by a boring-operation, so as to provide a finished surface, extending around the end-wall at right angles to the motor-shaft. The end-wall 2 of the statorframe has a plurality of axially extending holes.

II therein, which pass through this machined surface I0 at various points around the frame, each hole corresponding to one brushholdermounting.

In our invention, it is possible, and therefore desirable, to utilize underhung brushholders I2, as distinguished from overhung brushholders. An underhung brushholder is characterized by two support-pins I3 which extend radially inwardly from an outer corner of the brushholder-frame, so that the brushholder is supported, from the lower ends of these pins, at a support-point which is close to the point where the brushes I4 bear on the commutator 6, thus providing a very desirable brushholder-mounting, which is not only inherently rigid, but which requires a minimum of overhead or radial space.

In the illustrated form of embodiment of ourv brushholder-mounting, the mounting for each brushholder comprises a pair of outer and. inner support-blocks I5 and I6 respectively, using the terms outer and inner as referring to the axial direction, the inner block being toward the inside of the machine, and the outer block being toward the end-wall 2. support-blocks I5 and I6 have two sets of approximately semi-cylindrical seats I! for clampingly embracing the support-pins I3 of the associated brushholder.

The outer support-block I5 has a flat surface in engagement with the flat machine surface III of the motor-frame, and it has a hole I3, between its two pin-engaging seats ll, said hole acting as a continuation of the corresponding axially extending hole II in the motor-frame. In carrying but our invention, it is an easy manufacturing-procedure to make the outer support-block I5 have a predetermined thickness which accurately spaces the two brushholder-pins I3 from the accurately machined surface I 0 of the motor-frame. In the process of assembling the brushholder- These outer and inner been turned back sufiiciently to loosen the clamping-engagement of the associated inner block l6 against the corresponding support-pins l3. In an explosion-resistant motor, designed to meet Bureau of Mines specifications, the nut-trapping head 24 is permanently and irremovably secured to the outer end of the stud 2|, as by being integrally formed therewith, or welded thereto, thus surface at various points around the frame; a plurality of underhung brushholders, each brushholder having two support-pins extending radially inwardly from an outer corner of the brushholder-frame; a plurality of pairs of outer and inner support-blocks, each pair having two sets of approximately semi-cylindrical seats for clampingly embracing the two support-pins of one of said brushholders; each of the outer supportblocks having a flat surface in engagement with the flat machined surface of the motor-frame, and having a hole between its two pin-engaging seats and acting as a continuation of one of the axially extending holes in the motor-frame, and being of a predetermined thickness for accurately spacing the two brushholder-pins from the acj curately machined surface of said motor-frame;

permanently preventing the complete removal of the nut 22.

As shown more clearly in Fig. 3, the stud 2| is rigidly or fixedly secured to its inner supportblock l6, but it is preferably removably secured thereto, in the sense that it can be removed only after the motor has been opened up, and after a setscrew 26 has been removed from an edge of the inner end of the stud 2|. According to this construction, the inner end of the stud 2| is screwed into a threaded hole 2! in the inner block l6, and then the stud is locked in place by means of the setscrew 26.

In the use of our improved brushholder-mounting, during the useful life of the motor, it will be noted that a simple loosening of the nut 22 will suifice to loosen the mounting of the associated brushholder I2, after which the brushholder can be entirely removed for replacement, if necessary, or it can be readily adjusted radially, so as to raise or lower the b-rushholder-frame with respect to the surface of the commutator 6. A simple tightening of the nut 22 restores the brushholder-mounting to its normal operative condition. The nut 22 is provided with a locking washer 29, or other means intended to prevent the accidental loosening of the nut, but if the nut should become loosened in service, the motor does not lose its explosion-resistant qualities, because the head 24 on the stud 2| prevents the complete removal of the nut, the stud 2| cannot become disengaged from the inner clampingblock l6, and the flame-sealing clearance between the stud 2| and the holes II and I8 gives the motor an explosionresistant characteristic, even when the nut 22 is loosened.

From the manufacturers standpoint, it has already been noted that our invention is extremely desirable, both from the standpoint of its low cost, and from the standpoint of the accuracywhich is practically obtainable.

While we have illustrated our invention in a single preferred form of embodiment, we wish it to be understood that our invention is not limited, in its broadest aspects, to all of the illustrated details. We desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language,

We claim as our invention:

1. A brushholder-mounting for an explosionresistant motor, comprising, in combination: a motor-frame having a flat, accurately machined, brushholder-supporting surface at right angles to the motor-shaft, said frame having a plurality of axially extending holes through said machined means for permanently retaining each of said outer support-blocks in its proper place against said machined surface; and a stud carried by eachof said inner support-blocks and extending through the corresponding holes in the associated outer supportablock and in the motor-frame, with a flame-sealing explosion-resistant clearance within said holes, each stud havin a nut threaded on it, to engage the outer surface of the motor-frame, and having means on its outer end for preventing the complete removal of said nut after it has been turned back sufiiciently to loosen the clamping-engagement of the associated brushholder.

2. A brushholder-mounting for a dynamo-elem tric machine, comprising, in combination: a machine-frame having an end-wall provided with a plurality of brushholdensupporting portions at various points around the frame, each of said brushholder-supporting portions including two spaced, radially extending, approximately semicylindrical seats in accurately predetermined positions, and each of said brushholder-supporting portions having an axially extending h01e between its two seats; a, lurality of underhung brushholders, each brushholder having two support-pins extending radially inwardly from an outer corner of the brush-holder-frame in position to lie against the two seats of one of said brushholder-supporting portions; a supplementary clamping-block for completing each brushholder-mounting-means, each clamping-block having two spaced, approximately semi-cylindrical seats for engaging the two support-pins of its associated brushholder; and a stud carried by each of said supplementary clamping-blocks and extending through the corresponding hole in the associated brushho-lder-supporting portions of the machine-frame, with some freedom of a limited amount of axial movement in said hole, each stud having a nut threaded on it, to engage the outer surface of the motor-frame, and having means on its outer end for preventing the accidental removal of said nut after it has been turned back sufiiciently to loosen the clamping-engagement of the associated brushholder.

3. The invention as defined in claim 1, characterized by each stud being threadedly carried by its associated support-block, and having a removable safety-device for looking it in place.

4. The invention as defined in claim 2, characterized by each stud being threadedly carried by its associated clamping-block, and having a removable safety-device for looking it in place.

JOHN E. PASTORET. JOHN W. MORROW. 

